Add additional thread cancellation checking when generating HTML for printing to ensure the current thread is not the main thread.
Add additional thread cancellation checking when generating HTML for printing to ensure the current thread is not the main thread.

git-svn-id: 6eeea455dc0e2ce42bed66071b2ee3651efe9ff5@1918 eefc5464-0a4a-0410-82e6-d75a05d1654a

svn2github/Sequel-Pro,svn2github/Sequel-Pro,svn2github/Sequel-Pro,havocbane/sequel-pro,havocbane/sequel-pro,havocbane/sequel-pro,svn2github/Sequel-Pro,havocbane/sequel-pro